1. Field of the Invention
The invention relates to an encapsulated multiple sheet or insulating glass glazing unit and method of fabricating the same.
2. Description of the Prior Art
Multiple glazing units generally comprise two or more sheets of glass spaced from one another to provide an insulating air space in the zone between the facing surfaces of the sheets. This air space is effective to reduce the transmission of heat energy through the unit due to conduction and convection. In one typical form of multiple glazed window, the sheets of glass are spaced from each other by a metal marginal edge spacer element extending around the periphery of the glass sheets. The glass sheets are generally adhered to the spacer element by a mastic composition forming a continuous film around the marginal edges of the sheets, between each sheet and the spacer element, to produce a primary hermetic seal. The spacer element is typically formed to hold a desiccant. Openings may be provided in the spacer element to establish communication between the air space of the unit and the desiccant so that moisture from the air within the unit may be absorbed by the desiccant. A resilient moisture resistant spacer element having a layer of mastic adhered thereto is preferably disposed around the peripheral edges of the glass sheet and the spacer element to provide a secondary hermetic seal. And finally, a channel member of substantially U-shaped cross-section is preferably affixed around the periphery of the unit to protect the peripheral edges of the glass sheets forming the unit.
A conventional method of assembling multiple glazed units, as described above, involves the application of the layer or bead of mastic that forms the primary hermetic seal along two opposite sides of the metal spacer element which is adapted to engage the inner facing surfaces of the glass sheets about the marginal edges thereof. The spacer element is then disposed between two preformed glass sheets, and the sheets are thereafter pressed together to cause the sheets to adhere to the spacer element and seal the internal air space between the facing surfaces of the sheets from the atmosphere. The final air space between the two sheets of glass is a function of the thickness of the spacer element and the thickness of the mastic layers between each side of the spacing element and the adjacent glass sheet.
A layer of mastic or a resilient, moisture-resistant strip with a layer of mastic adhered thereto is then placed around the peripheral edges of the sheets of glass and the spacer element to form the secondary hermetic seal. A channel member formed of metal, such as stainless steel, for example, is thereafter affixed around the periphery of the unit. The angle that the flanges or sides of the channel member form with the central or web portion of the channel member is slightly less than 90 degrees. When the channel member is affixed to the edges of the glass sheets, the sides are held apart to allow the glass to be inserted therebetween. The sides are then released permitting them to spring back into contact with the faces of the glass sheets and is maintained in such position under tension. The foregoing, as well as other similar multiple glazed window constructions, is fully disclosed and illustrated in U.S. Pat. Nos. 2,838,810, 2,964,809, and 3,280,523.
Also, another type of multiple glazed unit and method of forming the same is illustrated and described in U.S. Pat. No. 2,624,979. The structure therein described employs at least two spaced apart sheets of glass wherein the peripheral edges of the top sheet are heated until they soften sufficiently to cause them to sag into contact the facing peripheral surface of the adjacent lower sheet. The glass in the region of contact at the marginal areas is heated to affect a sufficient degree of softening to cause a fusion between the mating glass surfaces to form a continuous weld around the innermost zone. The unit is then typically annealed and finally may be placed in a preformed frame assembly preparatory to being mounted in an opening of a building, for example.
Typically, the manufacture of the above multiple glazed insulating glass units requires a number of manufacturing and handling steps, preparatory to being ready for insertion into a building opening.